The Applicant's Assignee's U.S. Pat. No. 5,470,305, issued 28 Nov. 1995, and U.S. Pat. No. 6,471,668, issued 29 Oct. 1992, both of which are incorporated herein by reference, disclose medical/surgical lavage devices. This type of device is generally in the form of a handpiece that includes pump that discharges a pulsed flow of irrigation solution at a body site to be cleaned. Typically, the lavage solution is discharged from the handpiece through a tip assembly to a target site on the body. It is further known to provide a suction line that extends from the tip assembly. Thus, a typical lavage device is designed to deliver a charge of solution at the target site. Then, the solution is drawn away from the site through the attached suction line.
Often, the irrigation solution is either sterile water or a saline solution. The solution is typically stored in a collapsible closed container with flexible walls. Often the container is a transparent bag.
The above devices are useful for cleaning wound sites. Lavage units are also used to remove debris and extraneous tissue from around target tissue in order to allow a further procedure to be performed on the target tissue. One such type of tissue to which it is known to apply a lavage solution is bone. Specifically, the lavage solution, which is often discharged in a pulse flow, is used to clean the bone and surrounding soft tissue in order to allow a further procedure to be performed on the bone itself.
There are, however, medical procedures during which it is desirable to do something more than simply clean the tissue subject to the procedure. For example, there are some situations wherein when it is appropriate to apply an antibiotic directly to a section of exposed tissue. This procedure may be called for when there is concern that the tissue, if left untreated, would be prone to infection. Alternatively, there may be situations wherein the likelihood of the tissue becoming infecting is minimized if a cleaning agent stronger than saline is applied to the tissue. Castile soap is one such cleaning agent. Also, during the process of fitting an orthopedic implant, it may be desirable to apply a bone growth compound to the exposed surface of the bone against which the implant is to be fitted.
When it is desirable to apply such agents directly to the target tissue, a clinician may have to use plural surgical instruments. Specifically, a first instrument, such as a syringe, is used to apply the therapeutic agent. A second instrument, a suction wand, may be needed to collect the run off volume of the therapeutic agent that is not absorbed into the tissue. If the target site is one that is also subjected to lavage cleaning, a third instrument, the lavage handpiece needs to be used.
Having to provide these different instruments adds to the overall expense of performing the medical procedure. Also, having to provide each of these instruments adds to both the clutter in the operating room and the number of instruments that may need to be near simultaneously employed at the surgical site. Having to so provide these numerous instruments can add to the complexity of the surgical procedure.
To reduce this complexity, some clinicians have been known inject a therapeutic agent into the bag containing the lavage solution. The actuation of the lavage handpiece results in the discharge of a blended solution to the target site. To date, there have been some efforts to introduce antibiotics or soaps to the surgical sites by the mixing of these agents into the solution bag prior to discharge.
This mixing of the therapeutic agent directly into the solution bag does make it possible to discharge a blended solution, a solution consisting of the basic lavage solution and the therapeutic agent, directly at a target site. However, there are some disadvantages associated with this protocol. One significant limitation is that once the therapeutic agent is introduced into the solution bag, the entire contents of the bag essentially become the blended solution. There may be instances when the procedure only requires a limited application of the blended solution followed by an application of a neutral solution. In this instance, in order for the procedure to continue, the bag with the blended solution must be removed and a new bag that only contains the neutral solution substituted therefore. Having to perform these steps can increase the overall time it takes to complete the procedure. Also, having to discard the one bag and provide the new bag adds to generation of waste. If the procedure calls for the sequential application of multiple blended solutions, then the waste generated could increase arithmetically.
Further, care must be taken to, in a sterile environment ensure that the proper volume therapeutic agent is added to the solution bag. This is to ensure that the blended solution contains the appropriate proportion of the therapeutic agent. However, even when the correct volume of therapeutic agent is added to the lavage bag, it can still be difficult to ensure that the appropriate proportion of therapeutic agent is discharged from the lavage handpiece. The difficulty arises because the therapeutic agent may have a specific gravity appreciably different from that of the lavage solution. For example, if the therapeutic agent has a relatively high specific gravity, it may settle in the bottom of the lavage bag. Often, the bag is spiked, the open port created, above its base. If the therapeutic agent owing to its high specific gravity settles below this point, it may not be discharged in sufficient volume. Alternatively, if the agent settles around the opening, it may be discharged in an excessively high concentration. Difficulties can also arise discharging a therapeutic agent with a relatively low specific gravity. In this circumstance, the agent may again not mix with the solution and, instead, float to the top of the bag. If the fluids in the lavage bag so stratify again, the agent may not be discharged in the appropriate proportion in order to accomplish the desired therapeutic effect.